In recent years, with the advent of electronic devices such as mobile phones and personal computers having a more sophisticated function or a smaller size, input apparatuses used to operate such devices also have been required to provide a secure operation with a favorable operation feeling.
FIG. 6 and FIG. 7 are a cross-sectional view and an exploded perspective view of conventional input apparatus 501, respectively. Input apparatus 501 includes: operation body 1 that has a spherical shape and that is made of insulating resin; and magnetic body 2 made of iron or permalloy for example. Magnetic body 2 has a substantially-spherical core and substantially-circular columnar protrusions 2A and 2B protruding from the core. Protrusions 2A and 2B radially protrude from the core to the exterior. Magnetic body 2 is buried in operation body 1.
Upper case 3 and lower case 4 both made of a thin metal plate have operation body 1 stored rotatably between the upper and lower cases. An upper part of operation body 1 protrudes through an opening hole in an upper surface of upper case 3.
Upper case 3 and lower case 4 storing operation body 1 are placed on an upper surface of retention body 6 via cover 5. Cover 5 has a substantially plate-like shape and is made of elastic material, such as rubber. Retention body 6 is made of insulating resin.
At upper and lower surfaces of film-like wiring board 7, a plurality of wiring patterns are formed. At a lower side of operation body 1, the upper surface of wiring board 7 has thereon substantially cylindrical magnet 8, such as a ferrite magnet, so that the north pole faces upward and the south pole faces downward, for example.
Magnetic detection element 9 has magnetic sensors, such as a plurality of Hall elements, arranged. Magnetic detection element 9 is mounted on the upper surface of wiring board 7 and faces operation body 1 with a predetermined space therebetween. Magnetic detection element 9 is surrounded by wiring board 7 that includes therein substantially U-shaped notch 7A.
Frame 10 made of a thin metal plate has an upper part fixed to retention body 6 and retains upper case 3 and lower case 4, and operation body 1 stored in this, magnet 8, and magnetic detection element 9 at predetermined positions.
FIG. 8 is a perspective view of frame 10. A bottom surface of frame 10 has substantially-rectangular plate spring 10A. One end of plate spring 10A is bent and the other end protrudes in an upward direction. While plate spring 10A is slightly deflected, an end of plate spring 10A depresses a lower surface of magnetic detection element 9 via wiring board 7 to allow an upper surface of magnetic detection element 9 to elastically contact a lower surface of lower case 4 to constitute input apparatus 501 (see FIG. 7).
Input apparatus 501 is attached to an operation section of an electronic device, such as a mobile phone or a personal computer, such that the upper part of operation body 1 is protruded. Magnetic detection element 9 is electrically connected to an electronic circuit of the device via a wiring pattern for example.
When the upper part of operation body 1 is operated with a finger by rotating the upper part from front to back and from side to side or in an oblique direction while a plurality of menus, such as names or song titles, or a cursor are displayed on a display unit, such as a liquid crystal display element, of the electronic device, magnetic body 2 buried in operation body 1 is rotated accordingly. When operation body 1 is rotated in the right direction for example, protrusion 2A of magnetic body 2 is firstly moved toward magnetic detection element 9.
Magnetic detection element 9 detects, via protrusion 2A, the magnetic flux of substantially-cylindrical magnet 8 provided at a lower side of operation body 1. When operation body 1 is continuously operated by being rotated in the right direction, protrusion 2A is moved away from magnetic detection element 9, and then, protrusion 2B is moved toward magnetic detection element 9. As a result, the magnetic flux of magnet 8 is detected by magnetic detection element 9 via protrusion 2B.
Then, the magnetic flux detected through protrusions 2A and 2B of magnetic body 2 having moved away from and toward magnetic detection element 9 is output by magnetic detection element 9 as voltage signals having a phase difference to the electronic circuit of the device. The electronic circuit uses this signal to detect the rotation direction and the rotation angle of operation body 1, and moves the cursor for example on the menu displayed on the display unit of the device by a distance corresponding to the rotation angle in the right direction for example.
A voltage signal is similarly output from magnetic detection element 9 when operation body 1 is operated by being rotated in the left direction, the front-and-rear direction, or an oblique direction between these directions. Then, the electronic circuit detects the rotation direction and the rotation angle of operation body 1 and the cursor for example is moved in the left direction, the up-and-down direction, or the oblique direction.
Specifically, a user can operate, while looking at the display unit of the device, operation body 1 by rotating operation body 1 in a predetermined direction to move the cursor for example displayed on a display means in a predetermined direction to thereby easily select the menu for example.
An input apparatus similar to conventional input apparatus 501 is disclosed in Japanese Patent Unexamined Publication No. 2009-259024.
In conventional input apparatus 501 shown in FIG. 6 to FIG. 8, an end of substantially-rectangular plate spring 10A of a bottom surface of frame 10 depresses the lower surface of magnetic detection element 9 to cause the upper surface of magnetic detection element 9 to elastically contact the lower surface of lower case 4. Thus, magnetic detection element 9 elastically contacts the lower surface of lower case 4 while being slightly inclined thereto. This consequently causes a slight error in the detected magnetic flux, which may make it difficult to accurately detect the rotation angle of operation body 1.